ON FISSIDENS 321 



4. A rare pseudo-dioicous state, in which the female plant is 

 small and poorly developed, and shows no trace of male inflor- 

 escence. As the capsules ripen, sterile axillary branchlets appear 

 at times, and these may ultimately produce antheridia. If 

 the main stem should innovate and eventually yield a second 

 crop of archegonia, it is probable that these shoots would 

 bear terminal male flowers. This, of course, is at present mere 

 supposition. 



5. Simple stems bearing terminal male flowers. These male 

 plants are not abundant, and the possibility must be borne in 

 mind that they may ultimately develop female flowers when older. 

 Of this, however, there is no evidence at present. Their origin 

 may be accounted for in several ways. They may arise from the 

 axillary buds or shoots of No. 1. These may under some con- 

 ditions be caducous, and, having rhizinous bases, would succeed 

 in establishing themselves as separate plants. They may also 

 originate from detached shoots of the rhizantoicous form. If 

 they arise from an original protonema, their full development may 

 have been arrested by starvation, resulting in a suppression of one 

 of the sexes. 



The utilisation of variations of inflorescence for the separation 

 of species of mosses and hepatics has been carried to excess by 

 some authors, notably in this genus, and in Webera, Bryum, 

 Cephalozia, etc. The more attention one pays to groups of plants 

 in which the species depend principally on the situation of the 

 inflorescence, the more one inclines to the opinion that this 

 feature is sometimes assigned an importance unv/arranted by its 

 reliability. In discussing this subject with Mr. W. E. Nicholson 

 in 1906, he wrote : " With regard to this point, I think it is better 

 to recognise that the inflorescence is heteroicous in some species, 

 and that species founded on inflorescence alone are often un- 

 sound." That Mr. H. N. Dixon {loc. cit.) holds similar views may 

 be inferred from the fact that he denies specific rank to Fissidens 

 inipar, F. minutuhis, and F. tmnarindifolius. The inconstancy 

 of the inflorescence in F. pusillus var. Wilsoni, as described 

 above, and in other species of Fissidens, must cause us to regard 

 with more or less suspicion the status of species founded mainly 

 on the position of the flowers in some groups of both mosses and 

 liverworts. 



Continuous observation of growing plants would be useful in 

 clearing up some of the difficulties regarding the inflorescence of 

 the var. IVilsoni, and also in determining the duration of the 

 plants. The smaller species of Fissidens do not appear to be of 

 ephemeral habit, Hke some kinds of Pottia, Ephemermn, etc., and 

 are perhaps never, strictly speaking, even annual. If the var. 

 Wilsom be considered as such, it must produce more than one 

 crop of capsules in the season, since well-developed plants 

 occasionally show young perichaetia, ripe fruit, and old perichaetia 

 from which the setae have fallen, on the same plant. The type, 

 F. pusilhis, may possibly be an annual species ; if so, the var. 

 Wilsoni probably represents a race derived from it of at least 



